The present invention relates to coolant heating systems such as those which are used in large vehicles. In particular, the present invention relates to fuel burning coolant heaters of the type which are used on school buses.
Diesel-fired coolant heaters are designed to provide supplemental heat to the coolant used in water cooled engines and their related heating systems.
Auxiliary heaters are used to pre-heat coolant in cold weather situations, and are used to supplement and maintain heat energy in coolant systems of large vehicles. It is convenient to have diesel-fired coolant heaters which are capable of operating on the same diesel fuel as the engine of the vehicle. Such coolant heaters draw from the same main fuel tank as does the vehicle engine.
Since diesel fuel is highly flammable, safety is a major factor in the design of coolant heating systems. This is particularly true in the case of school buses, which are used to transport children. One of the ways in which the safety of a system can be enhanced is to make it easily accessible. By providing a system which can be easily serviced, problems which would otherwise result in accidents can be avoided.
Another possible hazard associated with diesel-fired coolant heaters is the possibility that the fuel supply line may be severed in an accident. If the fuel line is severed, and the fuel pump continues to operate, significant amounts of fuel can be spilled, resulting in a significant fire hazard.
Yet another problem associated with coolant heating systems is the presence of air in the coolant lines. The presence of air pockets may result in malfunctioning of the pumps which are used to cause coolant flow. If the pumps stall, overheating can result.
Therefore, it is an object of the present invention to provide a coolant heating system which reduces the possibility of accidents.
Another object of the present invention is to provide a coolant heating system which is easily serviced and inspected.
Still another object of the present invention is to provide a coolant heating system in which spillage of fuel is prevented in the event of an accident.
Yet another object of the present invention is to provide a coolant heating system in which air bubbles are removed from the coolant.
These and other objects and advantages of the invention are obtained with a coolant heating system in which an impact switch is used to stop the operation of a fuel pump upon a predetermined level of impact. The impact switch, which is more sensitive to lateral impact than vertical impact, is designed to stop the operation of the fuel pump when the switch is impacted.
The system includes a deaeration tank through which coolant is circulated. The deaeration tank allows air bubbles to rise to the top of the tank, while coolant is pumped from the bottom. The coolant heating system of the present invention is comprised of a heating unit which is mounted on a panel which slides in and out from a position from beneath a floor of a bus. The sliding panel allows for easy access to the components of the heating system, so that they can be easily serviced and inspected.
The objects and advantages of the invention will be better understood by reading the following specification in conjunction with the accompanying drawings.